Preparation method of electromagnetic wave absorbent and electromagnetic wave absorbent

Abstract

The invention discloses a preparation method of an electromagnetic wave absorbent and the electromagnetic wave absorbent, and the preparation method of the electromagnetic wave absorbent comprises the following steps: obtaining raw materials including acrylic acid, polyvinyl alcohol and MXene powder, and preparing MXene porous aerogel based on the raw materials; preparing a hollow CoS nanosphere; carrying out modification treatment on the hollow CoS nanospheres; and combining the MXene porous aerogel with the hollow CoS nanospheres subjected to the modification treatment, so as to prepare the light three-dimensional porous wave-absorbing aerogel. The porous structure of the aerogel and the hollow structure of the hollow CoS nanosphere can cooperate with each other, and after cooperation, the impedance of the aerogel and the hollow structure of the hollow CoS nanosphere is close to that of a free space, so that impedance mismatch can be reduced, and magnetic loss of electromagnetic waves can be well carried out.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave absorbers, and in particular to a preparation method of an electromagnetic wave absorber and the electromagnetic wave absorber. Background Art

[0002] With the development of 5G technology, the application of electronic devices and the Internet has become more extensive, but it is inevitable that electromagnetic interference affects almost the entire electronic and electrical system. From daily life, military activities to space exploration, considering the need for data security, the impact of electromagnetic waves on military electronic equipment, and potential health risks to humans, developing and designing high-efficiency electromagnetic wave absorbers with thin thickness, light weight, strong absorption strength and wide bandwidth is one of the effective ways to solve these problems.

[0003] As a new type of two-dimensional material, MXene has been widely used in sensors, energy storage, thermal conductive materials, biomedicine, electromagnetic absorption and other fields due to its advantages such as large specific surface area, good conductivity, controllable nanolayer thickness, and adjustable components. However, its high conductivity can easily cause impedance mismatch, causing a large amount of electromagnetic wave reflection and secondary pollution. Therefore, it is often balanced through structural design, such as introducing gradient isolation structures, porous structures, etc., or introducing magnetic materials to adjust electromagnetic parameters to achieve the purpose of absorption. However, existing methods cannot well improve the above problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of an electromagnetic wave absorber and the electromagnetic wave absorber, which can reduce impedance mismatch and effectively treat magnetic loss of electromagnetic waves.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0006] A method for preparing an electromagnetic wave absorber, comprising:

[0007] Obtaining raw materials including acrylic acid, polyvinyl alcohol and MXene powder, and preparing MXene porous aerogel based on the raw materials;

[0008] Preparation of hollow CoS nanospheres;

[0009] Modifying the hollow CoS nanospheres;

[0010] The MXene porous aerogel is combined with the modified hollow CoS nanospheres to prepare a lightweight three-dimensional porous microwave-absorbing aerogel.

[0011] Furthermore, the preparation of the MXene porous aerogel includes:

[0012] placing polyvinyl alcohol in deionized water, heating and stirring, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0013] Adding ammonium persulfate thermal initiator and MXene powder to acrylic acid monomer to obtain a mixed solution;

[0014] After subjecting the mixed solution to ultrasonic treatment, mixing it with the polyvinyl alcohol aqueous solution, and stirring in a water bath to obtain a uniform mixture;

[0015] The uniform mixture is allowed to stand to achieve automatic cross-linking and gelation, and then freeze-dried to obtain a MXene porous aerogel.

[0016] Further, the heating temperature is 80°C to 100°C;

[0017] The heating and stirring time is 3h to 5h.

[0018] Further, the standing time is 20h to 28h;

[0019] The freeze-drying time is 40h to 56h.

[0020] Furthermore, the preparation of the hollow CoS nanospheres includes:

[0021] Disperse hexadecyltrimethylammonium bromide in ethylene glycol and dissolve CoCl 2 6H 2 O, to obtain a mixed solution;

[0022] The mixed solution is subjected to ultrasonic treatment to obtain a suspension;

[0023] Adding thiourea to the suspension and stirring until a uniform red solution is formed;

[0024] The red solution was sealed and subjected to a hydrothermal reaction, and after cooling, it was washed alternately with deionized water and anhydrous ethanol to prepare hollow CoS nanospheres.

[0025] Further, the red solution is sealed in an autoclave to carry out a hydrothermal reaction.

[0026] Furthermore, the modification treatment of the hollow CoS nanospheres includes:

[0027] The hollow CoS nanospheres were added to a hexadecyltrimethylammonium bromide solution for ultrasonic treatment, and then the excess hexadecyltrimethylammonium bromide solution was washed with deionized water.

[0028] Furthermore, the MXene porous aerogel is combined with the modified hollow CoS nanospheres by an electrostatic self-assembly method.

[0029] Furthermore, the step of combining the MXene porous aerogel with the modified hollow CoS nanospheres by electrostatic self-assembly includes:

[0030] placing the modified hollow CoS nanospheres in deionized water to obtain a hollow CoS nanosphere dispersion;

[0031] Soaking the MXene porous aerogel in the hollow CoS nanosphere dispersion for electrostatic self-assembly, and then washing with deionized water;

[0032] After washing, the product is dried to prepare a lightweight three-dimensional porous wave-absorbing aerogel.

[0033] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0034] An electromagnetic wave absorber is prepared by the above-mentioned method for preparing an electromagnetic wave absorber.

[0035] The beneficial effects of the present invention are as follows: MXene porous aerogel is prepared with acrylic acid (AA), polyvinyl alcohol (PVA), and MXene powder as raw materials, and then a lightweight three-dimensional porous absorbing aerogel is prepared by combining modified hollow CoS nanospheres with MXene porous aerogel. The porous structure of the aerogel and the hollow structure of the hollow CoS nanospheres can cooperate with each other. The porosity of the aerogel can effectively reduce the impedance mismatch, allowing electromagnetic waves to enter the pores for absorption. In addition, the hollow CoS has magnetism and can cause magnetic loss of electromagnetic waves, and the electromagnetic waves are absorbed by synergistic action. After the synergy, its impedance is close to the impedance of free space, so the impedance mismatch can be reduced, thereby effectively causing magnetic loss of electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is a flowchart of a method for preparing an electromagnetic wave absorber according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0038] The preparation method of the electromagnetic wave absorber and the electromagnetic wave absorber of the present application can be applied to any scene where electromagnetic wave absorption is required, and the following is an explanation through specific implementation methods:

[0039] In an alternative embodiment, please refer to Figure 1 , a method for preparing an electromagnetic wave absorber, comprising the steps of:

[0040] S1. Obtaining raw materials including acrylic acid, polyvinyl alcohol and MXene powder, and preparing MXene porous aerogel based on the raw materials;

[0041] Wherein, the preparation of the MXene porous aerogel comprises:

[0042] placing polyvinyl alcohol in deionized water, heating and stirring, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0043] In another optional embodiment, the heating temperature is 80°C to 100°C;

[0044] The heating and stirring time is 3h to 5h;

[0045] Polyvinyl alcohol: 0.5 g to 1 g;

[0046] Deionized water is 10mL to 20mL;

[0047] Adding ammonium persulfate thermal initiator and MXene powder to acrylic acid monomer to obtain a mixed solution;

[0048] In another optional embodiment, the acrylic acid monomer is 5 g to 10 g;

[0049] Ammonium persulfate: 0.05 g to 0.1 g;

[0050] MXene powder is 0.5g to 1g

[0051] After subjecting the mixed solution to ultrasonic treatment, mixing it with the polyvinyl alcohol aqueous solution, and stirring in a water bath to obtain a uniform mixture;

[0052] Among them, the ultrasonic treatment time is 3min to 5min;

[0053] The stirring time in the water bath is 10 to 15 minutes;

[0054] The uniform mixture is allowed to stand to achieve automatic cross-linking and gelation, and then freeze-dried to obtain a MXene porous aerogel;

[0055] Among them, the static time is 20h to 28h;

[0056] The freezing temperature is -40℃ to -50℃;

[0057] Freeze drying time is 40h to 56h;

[0058] S2, preparation of hollow CoS nanospheres;

[0059] Specifically, the preparation of the hollow CoS nanospheres includes:

[0060] Disperse cetyltrimethylammonium bromide (CTAB) in ethylene glycol and dissolve CoCl 2 6H 2 O, to obtain a mixed solution;

[0061] Among them, hexadecyltrimethylammonium bromide, ethylene glycol and CoCl 2 6H 2 The value ranges of O are:

[0062] Hexadecyltrimethylammonium bromide: 4mmoL~6mmoL;

[0063] Ethylene glycol: 50mL~80mL;

[0064] CoCl2·6H2O: 4mmoL~6mmoL;

[0065] The mixed solution is subjected to ultrasonic treatment to obtain a suspension;

[0066] Among them, the ultrasonic treatment time is 0.5h to 1h;

[0067] Adding thiourea to the suspension and stirring until a uniform red solution is formed;

[0068] Wherein, thiourea is 16 mmol to 20 mmol;

[0069] The stirring time is 1h to 1.5h;

[0070] The red solution is sealed and subjected to a hydrothermal reaction, and after cooling, it is washed alternately with deionized water and anhydrous ethanol to prepare hollow CoS nanospheres; in a specific implementation, the red solution is sealed in an autoclave for a hydrothermal reaction;

[0071] The hydrothermal temperature is 200°C to 230°C;

[0072] The duration of hydrothermal treatment is 16h to 20h;

[0073] The number of alternating washes is 3 to 5 times;

[0074] S3, modifying the hollow CoS nanospheres;

[0075] The modification treatment of the hollow CoS nanospheres comprises:

[0076] The hollow CoS nanospheres were added to a hexadecyltrimethylammonium bromide solution and subjected to ultrasonic treatment, and then the excess hexadecyltrimethylammonium bromide solution was washed with deionized water;

[0077] Among them, the hollow CoS nanospheres are 0.5g to 1g;

[0078] 20 mL to 30 mL of hexadecyltrimethylammonium bromide solution, with a concentration of 2 mg / mL to 5 mg / mL;

[0079] The duration of ultrasonic treatment is 1h to 1.5h;

[0080] S4, combining the MXene porous aerogel with the modified hollow CoS nanospheres to prepare a lightweight three-dimensional porous absorbing aerogel;

[0081] In another optional embodiment, the MXene porous aerogel is combined with the modified hollow CoS nanospheres by an electrostatic self-assembly method;

[0082] Specifically, the modified hollow CoS nanospheres are placed in deionized water to obtain a hollow CoS nanosphere dispersion;

[0083] Soaking the MXene porous aerogel in the hollow CoS nanosphere dispersion for electrostatic self-assembly, and then washing with deionized water;

[0084] After washing, the mixture is dried to obtain a lightweight three-dimensional porous microwave-absorbing aerogel;

[0085] Among them, the weight of the hollow CoS nanospheres after modification is 0.3g to 0.6g;

[0086] Deionized water is 30mL to 60mL;

[0087] The soaking time is 30 to 45 minutes;

[0088] The number of washes is 3 to 5 times;

[0089] Drying temperature is 60℃ to 80℃;

[0090] The drying time is 18h to 24h.

[0091] In another optional embodiment, an electromagnetic wave absorber is prepared by the method for preparing an electromagnetic wave absorber described in any of the above embodiments.

[0092] The following is a specific example to illustrate how to prepare the above-mentioned lightweight three-dimensional porous absorbing aerogel:

[0093] Embodiment 1

[0094] (1) Preparation of MXene aerogel: 1 g of PVA was weighed and placed in 20 mL of deionized water. The solution was heated and stirred at 90 °C for 3 h, and then cooled to room temperature to obtain a PVA aqueous solution. 0.1 g of ammonium persulfate thermal initiator and 0.5 g of MXene powder were added to 10 g of AA monomer. The mixed solution was ultrasonically treated for 3 min, poured into the above PVA aqueous solution, and stirred in a water bath for 10 min to obtain a uniform mixture. The mixture was poured into a mold and allowed to stand for 24 h to allow it to automatically crosslink and gel. Then, it was poured into a plastic mold and freeze-dried at -40 °C for 48 h to obtain a MXene aerogel.

[0095] (2) Preparation of hollow CoS nanospheres: 4 mmol of hexadecyltrimethylammonium bromide (CTAB) was dispersed in 50 mL of ethylene glycol, and then 4 mmol of CoCl2·6H2O was dissolved in the above solution, and the mixed solution was treated with ultrasound for 30 min. Subsequently, 16 mmol of thiourea was added to the suspension and stirred for 1 h until a uniform red solution was formed. The prepared solution was sealed in a 100 mL lined autoclave and subjected to hydrothermal reaction at 200 °C for 16 h. Finally, the cooled solution was washed alternately with deionized water and anhydrous ethanol for 3 times, and the prepared hollow CoS nanospheres were dried in a vacuum oven at 60 °C for 24 h.

[0096] (3) Preparation of lightweight three-dimensional porous absorbing aerogel: 1 g of hollow CoS nanospheres was added to 30 mL of CTAB solution (2 mg / mL) and ultrasonically treated for 1 h. The excess CTAB was then washed with deionized water. 0.5 g of the modified hollow CoS nanospheres was placed in 50 mL of deionized water. The MXene aerogel was immersed in the hollow CoS dispersion for electrostatic self-assembly. After soaking for 30 min, it was rinsed with deionized water three times and dried in a vacuum drying oven at 60 °C for 24 h to obtain a lightweight three-dimensional porous absorbing aerogel.

[0097] Embodiment 2

[0098] (1) Preparation of MXene aerogel: Weigh 1g of PVA and place it in 10mL of deionized water. Heat and stir at 80℃ for 5h, then cool the solution to room temperature to obtain a PVA aqueous solution. Add 0.1g of ammonium persulfate thermal initiator and 0.5g of MXene powder to 5g of AA monomer, and ultrasonically treat the mixed solution for 3min. Pour it into the above PVA aqueous solution, stir in a water bath for 10min to obtain a uniform mixture, pour it into a mold and let it stand for 24h to allow it to automatically crosslink and gel, then pour it into a plastic mold and freeze-dry at -40℃ for 48h to obtain MXene aerogel;

[0099] (2) The preparation of hollow CoS nanospheres was consistent with that in Example 1;

[0100] (3) Preparation of lightweight three-dimensional porous absorbing aerogel: 0.5 g of hollow CoS nanospheres were added to 20 mL of CTAB solution (5 mg / mL) and ultrasonically treated for 1 h. The excess CTAB was then washed with deionized water. 0.3 g of the modified hollow CoS nanospheres were placed in 30 mL of deionized water. The MXene aerogel was immersed in the hollow CoS dispersion for electrostatic self-assembly. After soaking for 30 min, it was rinsed with deionized water three times and dried in a vacuum drying oven at 60 °C for 24 h to obtain a lightweight three-dimensional porous absorbing aerogel.

[0101] The lightweight three-dimensional porous absorbing aerogel prepared in this application introduces a variety of electromagnetic wave loss mechanisms to achieve the purpose of efficient electromagnetic wave absorption, among which:

[0102] Example 1 The aerogel thickness is only 1.82 mm, the RLmin is -60.4 dB at 12.56 GHz, and the effective absorption band is up to 3.25 GHz;

[0103] The aerogel thickness of Example 2 is 1.54 mm, the RLmin is -47.4 dB at 14.6 GHz, and the effective absorption band is up to 3.56 GHz.

[0104] In summary, the present invention provides a method for preparing an electromagnetic wave absorber and an electromagnetic wave absorber. First, AA, PVA, and MXene powders are used as raw materials to prepare MXene porous aerogel by freeze drying, then hollow CoS nanospheres are prepared and modified, and finally the modified hollow CoS nanospheres are combined with MXene aerogel by electrostatic self-assembly to prepare a lightweight three-dimensional porous wave absorbing aerogel. The porous structure of the aerogel and the hollow structure of the hollow CoS nanospheres can cooperate with each other. After the cooperation, the impedance is close to the impedance of free space, so the impedance mismatch can be reduced, thereby effectively performing magnetic loss on electromagnetic waves.

[0105] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing an electromagnetic wave absorber, characterized in that: include: Obtaining raw materials including acrylic acid, polyvinyl alcohol and MXene powder, and preparing MXene porous aerogel based on the raw materials; Preparation of hollow CoS nanospheres; Modifying the hollow CoS nanospheres; The MXene porous aerogel is combined with the modified hollow CoS nanospheres to prepare a lightweight three-dimensional porous microwave-absorbing aerogel.

2. The method for preparing an electromagnetic wave absorber according to claim 1, characterized in that: The preparation of the MXene porous aerogel comprises: placing polyvinyl alcohol in deionized water, heating and stirring, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution; Adding ammonium persulfate thermal initiator and MXene powder to acrylic acid monomer to obtain a mixed solution; After subjecting the mixed solution to ultrasonic treatment, mixing it with the polyvinyl alcohol aqueous solution, and stirring in a water bath to obtain a uniform mixture; The uniform mixture is allowed to stand to achieve automatic cross-linking and gelation, and then freeze-dried to obtain a MXene porous aerogel.

3. The method for preparing an electromagnetic wave absorber according to claim 2, characterized in that: The heating temperature is 80°C to 100°C; The heating and stirring time is 3h to 5h.

4. The method for preparing an electromagnetic wave absorber according to claim 2, characterized in that: The standing time is 20h to 28h; The freeze-drying time is 40h to 56h.

5. A method for preparing an electromagnetic wave absorbent according to any one of claims 1 to 4, characterized in that: The preparation of the hollow CoS nanospheres comprises: Dispersing hexadecyltrimethylammonium bromide in ethylene glycol, and dissolving CoCl2·6H2O therein to obtain a mixed solution; The mixed solution is subjected to ultrasonic treatment to obtain a suspension; Adding thiourea to the suspension and stirring until a uniform red solution is formed; The red solution was sealed and subjected to a hydrothermal reaction, and after cooling, it was washed alternately with deionized water and anhydrous ethanol to prepare hollow CoS nanospheres.

6. The method for preparing an electromagnetic wave absorber according to claim 5, characterized in that: The red solution was sealed in an autoclave for hydrothermal reaction.

7. A method for preparing an electromagnetic wave absorber according to any one of claims 1 to 4, characterized in that: The modification treatment of the hollow CoS nanospheres comprises: The hollow CoS nanospheres were added to a hexadecyltrimethylammonium bromide solution for ultrasonic treatment, and then the excess hexadecyltrimethylammonium bromide solution was washed with deionized water.

8. A method for preparing an electromagnetic wave absorber according to any one of claims 1 to 4, characterized in that: The MXene porous aerogel is combined with the modified hollow CoS nanospheres by an electrostatic self-assembly method.

9. The method for preparing an electromagnetic wave absorber according to claim 8, characterized in that: The step of combining the MXene porous aerogel with the modified hollow CoS nanospheres by an electrostatic self-assembly method comprises: placing the modified hollow CoS nanospheres in deionized water to obtain a hollow CoS nanosphere dispersion; The MXene porous aerogel is immersed in the hollow CoS nanosphere dispersion for electrostatic self-assembly, and then washed with deionized water; After washing, the product is dried to obtain a lightweight three-dimensional porous wave-absorbing aerogel.

10. An electromagnetic wave absorber, characterized in that: The electromagnetic wave absorber is prepared by the method for preparing an electromagnetic wave absorber according to any one of claims 1 to 9.

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